THE POTENTIAL ENERGY SURFACE OF GUANINE IS NOT FLAT : AN AB INITIO STUDY WITH LARGE BASIS SETS AND HIGHER ORDER ELECTRON CORRELATION CONTRIBUTIONS
THE POTENTIAL ENERGY SURFACE OF GUANINE IS NOT FLAT : AN AB INITIO STUDY WITH LARGE BASIS SETS AND HIGHER ORDER ELECTRON CORRELATION CONTRIBUTIONS
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鸟嘌呤的势能面不平坦：大基组和高阶电子相关贡献的从头算研究
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发表时间：
1998
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通讯作者：
J. Leszczynski
中科院分区：
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作者：
J. Leszczynski
研究了鸟嘌呤分子的势能面。采用从头算LCAO-MO方法，在MP2水平上，采用d-和p-极化函数增广的双电子基组（6- 31 G（d，p）），研究了7种不同形式鸟嘌呤的非平面几何构型.其中研究的形式是四个最低能量的互变异构体，一个旋转异构体，和两个过渡态形式的质子转移之间的氧代和羟基的鸟嘌呤N（7）H和N（9）H互变异构体。我们对互变异构体的相对稳定性的最佳估计包括在MP2/6- 31 G（d，p）参考几何结构下在MP4（SDTQ）/6- 31 G（d，p），MP4（SDQ）/6- 311 G（d，p）和MP2/6-311++G（df，pd）水平上计算的电子相关贡献。在鸟嘌呤的MP2能级PES上，有三种互变异构体（和一种旋转异构体）位于10 kJ mol ~（-1）以内.计算的质子转移的能垒大于150 kJ mol-1，并不改变超过几个kJ mol-1的SCRF模型的应用后。
An investigation of the potential energy surface (PES) of guanine was performed. The (nonplanar) molecular geometries of seven different forms of guanine were studied using the ab initio LCAO-MO method at the MP2 level with valence double-ζ basis sets augmented by d- and p-polarization functions (6-31G(d,p)). Among the studied forms are the four lowest energy tautomers, one rotamer, and two transition state forms for proton transfer between oxo and hydroxo tautomers of guanine N(7)H and N(9)H tautomers. Our best estimation of the relative stabilities of the tautomers includes electron correlation contributions calculated at the MP2/6-31G(d,p) reference geometries at the MP4(SDTQ)/6-31G(d,p), MP4(SDQ)/6-311G(d,p), and MP2/6-311++G(df,pd) levels. Three tautomers (and one rotamer) are located within 10 kJ mol-1 on the MP2 level PES of guanine. The calculated energy barriers for the proton transfer are larger than 150 kJ mol-1 and do not change by more than a few kJ mol-1 upon application of the SCRF model ba...